Steady boundary layer blowing as a means to remove loss generating separated flow in gas turbine engines is well established. The source of the blowing flow comes from higher pressure regions of the engine or an auxiliary source. The extraction of this high-pressure flow results in a penalty on overall engine performance and efficiency. Prior art on control of boundary layer separation typically reports that the use of unsteady blowing reduces the necessary amount of mass required by steady blowing by factors ranging from 2 to about 100. A means of improving blowing efficiency is to introduce unsteady blowing through fluidic oscillators where a flow of fluid is pulsed without mechanical actuators into the boundary layer upstream of the separation point. However, the frequency, amplitude, and phase of the unsteadiness are critical to proper application of unsteady blowing for boundary layer control.
Therefore there is need of a method of implementing unsteady boundary layer injection using fluidic oscillators. In particular, there is a need for new techniques for operating unsteady fluidic oscillators that take into account the dynamics of the overall fluidic dynamic system.